JP6205274B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor.

  As a conventional electric motor, as shown in FIG. 7, a motor including a rotor 101 and a stator 201 and the rotor 101 and the stator 201 being accommodated in a case 301 (housing) is known (for example, see Patent Document 1). ). The rotor 101 includes a rotor shaft 111, a rotor core 121 attached to the rotor shaft 111, and a pair of end plates 131 and 131. The stator 201 includes a stator core 211 and a coil 221 and is formed in an annular shape as a whole.

  Here, the outer cylinder ring 401 is used to fix the stator 201 to the case 301. The outer cylindrical ring 401 has an inner peripheral surface pressed against the outer peripheral surface of the stator 201 and applies a tightening load toward the inner peripheral side to the stator 201, while the outer peripheral surface is applied to the inner peripheral surface of the case 301. Press contact. The outer ring 401 has a radial dimension that is different between the axial ends 401a and 401c of the stator 201 and the axial intermediate portion 401b. The outer ring 401 is tightened to the stator 201 at both ends 401a and 401c larger than the intermediate portion 401b. Apply load. Thereby, it is intended to secure a tightening load necessary for the removal of the stator 201 by the axial end portions 401a and 401c.

JP 2010-246259 A

  By the way, in a general electric motor, when a stator (corresponding to the above-described stator 201) is fitted to an inner peripheral surface of a housing (corresponding to the above-described outer cylinder ring 401 or case 301), shrink fitting is performed. Often used.

  Here, since the stator is composed of a member such as iron having a relatively small linear expansion coefficient, and the housing is composed of a member such as aluminum having a relatively large linear expansion coefficient, the stator and the housing are connected by shrink fitting. When assembled, the housing is deformed to the inner peripheral side (direction approaching the stator) at both axial ends at low temperatures, and is deformed to the outer peripheral side (direction away from the stator) at the axial intermediate portion. That is, the housing is deformed into a barrel shape at a low temperature.

  In this case, very large stress is applied to both ends in the axial direction of the stator due to contact with the housing, and iron loss increases. In addition, since a large stress is applied to the housing that is in contact with both axial end portions of the stator, damage may occur. Furthermore, since the axially intermediate portion of the stator is separated from the housing, the holding force of the housing is reduced and noise is increased.

  In particular, when the technique described in Patent Document 1 is applied, the outer ring 401 gives a larger tightening load to the stator 201 at both end portions 401a and 401c than the intermediate portion 401b. There is a risk that it will become more prominent.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an electric motor capable of reducing stress applied to both axial end portions of a stator and suppressing noise generation. .

In order to achieve the above object, the invention according to claim 1
A shaft (for example, a shaft 11 in an embodiment described later);
A rotor (e.g., a rotor 12 in an embodiment described later) fitted on the shaft;
A stator (for example, a stator 13 in an embodiment described later) disposed on the outer peripheral side of the rotor;
A housing (for example, a housing 20 in an embodiment described later) that holds the stator on an inner peripheral surface (for example, an inner peripheral surface 20a in an embodiment described later);
In an electric motor (for example, an electric motor 10 in an embodiment described later),
The linear expansion coefficient of the housing is larger than the linear expansion coefficient of the stator,
The radial thickness of the inner peripheral surface of the housing is characterized by being thinner at both axial end portions than at the axial intermediate portion.

In addition to the structure of Claim 1, the invention according to Claim 2
Inside the housing, a refrigerant flow path (for example, a refrigerant flow path 30 in an embodiment described later) that extends in the circumferential direction and flows the refrigerant is formed,
A radial distance from the inner peripheral surface to the refrigerant flow path (for example, radial distances A and B in the embodiments described later) is shorter at both axial end portions than at the axial intermediate portion.

According to the first aspect of the present invention, since the radial thickness of the inner peripheral surface of the housing holding the stator is thinner at both axial ends than the axial intermediate portion, the rigidity of the housing is higher than that of the axial intermediate portion. It decreases at both axial ends.
Therefore, when the rigidity at both axial ends of the housing is reduced, the stress applied to both axial ends of the stator is relieved, and an increase in iron loss can be suppressed. In addition, since the stress applied to the housing is reduced, it is possible to prevent the housing from being damaged.
Further, since the rigidity in the axial middle part of the housing is increased, barrel deformation at low temperatures can be prevented, and the distance from the housing in the axial middle part of the stator is also reduced, so that the stator is firmly held by the housing. Therefore, noise generation can be suppressed.

  According to the invention of claim 2, by changing the shape of the refrigerant flow path and the position where the refrigerant flow path is provided, the radial thickness of the inner peripheral surface of the housing can be adjusted without changing the outer shape of the housing. The rigidity in the axial direction of the housing can be changed by changing the direction.

It is a partial sectional view showing one embodiment of an electric motor concerning the present invention. It is principal part sectional drawing of an electric motor. It is a graph which shows the magnitude | size of the noise in the boss | hub part of a housing at the time of fixing the radial direction thickness of an inner cylinder, and changing the radial direction thickness of an outer cylinder. It is a graph which shows the magnitude | size of the noise in a cover at the time of fixing the radial direction thickness of an inner cylinder, and changing the radial direction thickness of an outer cylinder. It is a graph which shows the magnitude | size of the noise in the boss | hub part of a housing at the time of fixing the radial direction thickness of an outer cylinder, and changing the radial direction thickness of an inner cylinder. It is a graph which shows the magnitude | size of the noise in a cover at the time of fixing the radial direction thickness of an outer cylinder, and changing the radial direction thickness of an inner cylinder. It is sectional drawing which shows the conventional electric motor.

  Hereinafter, an embodiment of an electric motor according to the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the electric motor 10 of the present embodiment includes a shaft 11, a rotor 12 that is externally fitted to the shaft 11, a stator 13 that is disposed on the outer peripheral side of the rotor 12, and the stator 13 that has an inner peripheral surface 20 a. And a housing 20 held by the The stator 13 includes a stator core 13a held on the inner peripheral surface 20a of the housing 20 and coils 13b provided on both axial sides of the stator core 13a. The stator 13 is made of a material such as iron, and the housing 20 is made of a material such as aluminum. Therefore, the linear expansion coefficient of the housing 20 is larger than the linear expansion coefficient of the stator 13.

  The housing 20 has a cylindrical shape, and an inner cylinder 21 in which the stator 13 is fixed to the inner peripheral surface (inner peripheral surface 20a of the housing 20) by shrink fitting, and an outer cylinder 22 disposed on the outer peripheral side of the inner cylinder 21. And having. Both ends of the inner cylinder 21 and the outer cylinder 22 in the axial direction are connected by a pair of column portions 23 and 24 extending in the circumferential direction and the radial direction. Inside the housing 20, more specifically, between the inner cylinder 21, the outer cylinder 22, and the pair of column portions 23, 24, there is a refrigerant flow path 30 that extends in the circumferential direction and flows a refrigerant (for example, cooling water). It is formed.

  The coolant channel 30 is formed in an annular shape, and its axial width is set to be slightly smaller than the axial width of the stator core 13a. Further, in the refrigerant flow path 30, first to third inner ribs 41 to 43 are provided side by side in the axial direction, connecting the inner cylinder 21 and the outer cylinder 22 in the radial direction and extending in the circumferential direction. The refrigerant flow path 30 is divided into first to fourth refrigerant flow path pieces 31 to 34 by the first to third inner ribs 41 to 43.

  In addition, the outer peripheral surface of the outer cylinder 22 of the housing 20 (the outer peripheral surface 20b of the housing 20) protrudes radially outward at a position that overlaps the first to fourth refrigerant channel pieces 31 to 34 in the axial direction. An outer rib 45 extending in the direction is provided.

  Here, as shown in FIG. 2, the inner peripheral surface from the first and fourth refrigerant flow path pieces 31, 34 located at both ends in the axial direction among the plurality of first to fourth refrigerant flow path pieces 31 to 34. The radial distance A up to 20a (the radial thickness of the inner cylinder 21 at the position overlapping the first and fourth refrigerant flow path pieces 31, 34 in the axial direction) is the second, Radial distance B from the third refrigerant flow path pieces 32, 33 to the inner peripheral surface 20a (the radial thickness of the inner cylinder 21 at the position overlapping the second and third refrigerant flow path pieces 32, 33 in the axial direction) ) Is set shorter than (A <B).

  As described above, since the linear expansion coefficient of the housing 20 is larger than the linear expansion coefficient of the stator 13, when the stator 13 and the housing 20 are assembled by shrink fitting, the housing 20 is not internal at both axial ends at low temperatures. There is a tendency to deform toward the peripheral side (direction approaching the stator 13) and to deform toward the outer peripheral side (direction away from the stator 13) in the axially intermediate portion.

  However, in the present embodiment, the radial distance A from the first and fourth refrigerant flow path pieces 31, 34 located at both axial end portions to the inner peripheral surface 20 a is the second, second located at the axial intermediate portion. 3 Since the refrigerant flow path pieces 32 and 33 are set to be shorter than the radial distance B from the inner peripheral surface 20a (A <B), the rigidity at both axial ends of the housing 20 is reduced, and the axial direction of the stator 13 is reduced. Stress applied to both ends can be relaxed, and an increase in iron loss can be suppressed. Moreover, since the stress applied to the housing 20 is also reduced, it is possible to prevent the housing 20 from being damaged. Furthermore, since the rigidity at the intermediate portion in the axial direction of the housing 20 is increased, barrel deformation at a low temperature can be prevented, and the separation distance from the housing 20 at the intermediate portion in the axial direction of the stator 13 is also reduced. The holding of 13 becomes strong, and it is possible to suppress noise generation.

  Further, the inner cylinder can be changed without changing the outer shape of the housing 20 by changing the shape of the refrigerant flow path 30 (first to fourth refrigerant flow path pieces 31 to 34) or the position where the refrigerant flow path 30 is provided. The radial thicknesses A and B of 21 can be changed in the axial direction to change the rigidity of the housing 20 in the axial direction.

  Further, the stator 13 has first and fourth refrigerant flow path pieces 31, 34 at both axial ends as compared to the radial distance B between the second and third refrigerant flow path pieces 32, 33 at the axial middle part. Since the cooling distance at both ends in the axial direction of the stator 13 is improved, it is easy to receive stress from the housing 20 and iron loss easily occurs. Efficiency can be improved.

(Example)
In the above-described embodiment, the radial distances A and B (the radial thickness of the inner cylinder 21) from the first to fourth refrigerant channel pieces 31 to 34 to the inner peripheral surface 20a of the housing 20 are changed in the axial direction. Thus, the rigidity in the axial direction of the housing 20 was changed, but the radial distance from the first to fourth refrigerant flow path pieces 31 to 34 to the outer peripheral surface 20b of the housing 20 (the radial thickness of the outer cylinder 22). It is also conceivable to change the rigidity of the housing 20 in the axial direction by changing in the axial direction. Therefore, the following analysis was performed as to which of the radial thicknesses of the inner cylinder 21 and the outer cylinder 22 contributes to noise reduction of the housing 20.

  3 and 4, noise (vibration) at a boss portion (not shown) of the housing 20 when the radial thickness of the inner cylinder 21 is fixed and the radial thickness of the outer cylinder 22 is changed. And the magnitude of noise in a cover (not shown) connected to the housing 20 in the axial direction to protect the motor 10 from the external environment. 5 and 6 show the magnitude of noise in the boss portion of the housing 20 when the radial thickness of the outer cylinder 22 is fixed and the radial thickness of the inner cylinder 21 is changed. The magnitude of noise in the cover is shown.

  3 and 4 that the noise reduction effect is low and the sensitivity to noise is low even when the radial thickness of the outer cylinder 22 is changed from 5 mm to 6 mm. On the other hand, according to FIGS. 5 and 6, it can be seen that when the radial thickness of the inner cylinder 21 is changed to 4 mm, 5 mm, and 6 mm, the noise reduction effect is large and the sensitivity to noise is high.

  As described above, when changing the rigidity of the housing 20 in the axial direction, changing the radial thickness of the inner cylinder 21 has a greater noise reduction effect than changing the radial thickness of the outer cylinder 22. It is clear that efficiency is good. Therefore, when the rigidity in the axial direction of the housing 20 is changed, the radial distance A from the first to fourth refrigerant flow path pieces 31 to 34 to the inner peripheral surface 20a of the housing 20 as in the above-described embodiment. , B (the radial thickness of the inner cylinder 21) is preferably changed in the axial direction.

  In addition, this invention is not limited to what was illustrated to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  For example, if the radial distance from the inner peripheral surface 20a of the housing 20 to the refrigerant flow path 30 is shorter at both axial end portions than the axial intermediate portion, the refrigerant flow path 30 is not necessarily limited to the first to third. It is not necessary to divide into the 1st-4th refrigerant | coolant flow path pieces 31-34 by the inner side ribs 41-43.

  Further, the refrigerant flow path 30 does not have to be formed inside the housing 20, and in this case, the radial thickness of the inner peripheral surface 20a of the housing 20 at the position overlapping the stator 13 in the axial direction is set to the intermediate in the axial direction. What is necessary is just to set so that it may become thin in the axial direction both ends rather than a part.

DESCRIPTION OF SYMBOLS 10 Electric motor 11 Shaft 12 Rotor 13 Stator 13a Stator core 13b Coil 20 Housing 20a Inner peripheral surface 20b Outer peripheral surface 21 Inner cylinder 22 Outer cylinder 23, 24 Pillar part 30 Refrigerant flow paths 31-34 Refrigerant flow path pieces 41-43 Inner rib (rib) )
45 Outer rib A, B Radial distance

Claims (2)

A shaft,
A rotor fitted on the shaft;
A stator disposed on the outer peripheral side of the rotor;
A housing for holding the stator on an inner peripheral surface;
In an electric motor comprising:
The linear expansion coefficient of the housing is larger than the linear expansion coefficient of the stator,
An electric motor characterized in that a radial thickness of an inner peripheral surface of the housing is thinner at both axial end portions than at an axial intermediate portion. Inside the housing is formed a refrigerant flow path that flows in the circumferential direction and flows the refrigerant,
The electric motor according to claim 1, wherein a radial distance from the inner peripheral surface to the refrigerant flow path is shorter at both axial end portions than at an axial intermediate portion.

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